5. Billboard Rentals - Very costly but can be very effective for branding or event advertising
Drive by the billboard several times both day and night to check its visibility
Look for obstructions, Trees, Utility Poles, etc.
How far away can the billboard be seen?
How many seconds does a driver have to read you ad?

6. Bus Advertising - Costly and not much control of your ad placement
What happens when the bus goes in the shop for repair? This can be a disaster for a time sensitive ad.
How often are the buses washed, particularly in the winter?

7. Roadside Signs - Affordable and effective
In most counties, these signs are a zoning violation and they will be picked up by the county and you may be fined.
Some counties allow them to go out on the weekend but must be picked up by Monday morning.